BASICS 9 of 19

A lamp emits lumens.

Light levels are measured in foot-candles, which is lumens per square foot. A typical indoor light level (offices) is 50 foot-candles.

A foot-candle is the light level one foot from a candle.

A candle emits 13 lumens; a 100 watt bulb emits about 1600 to 1750 lumens, a 4 foot fluorescent lamp emits about 3000 lumens.

If you take all the lumens emitted by a lamp and focus it on a small area, you will have very high foot-candles of illumination, if you spread it out over a large area you will have lower foot-candles.